lavr: add x86-optimized functions for mixing 2 to 1 s16p with float coeffs

libavresample/x86/util.asm

@@ -0,0 +1,34 @@
+;******************************************************************************
+;* x86 utility macros for libavresample
+;* Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
+;*
+;* This file is part of Libav.
+;*
+;* Libav is free software; you can redistribute it and/or
+;* modify it under the terms of the GNU Lesser General Public
+;* License as published by the Free Software Foundation; either
+;* version 2.1 of the License, or (at your option) any later version.
+;*
+;* Libav is distributed in the hope that it will be useful,
+;* but WITHOUT ANY WARRANTY; without even the implied warranty of
+;* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;* Lesser General Public License for more details.
+;*
+;* You should have received a copy of the GNU Lesser General Public
+;* License along with Libav; if not, write to the Free Software
+;* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+;******************************************************************************
+
+%macro S16_TO_S32_SX 2 ; src/low dst, high dst
+%if cpuflag(sse4)
+    pmovsxwd     m%2, m%1
+    psrldq       m%1, 8
+    pmovsxwd     m%1, m%1
+    SWAP %1, %2
+%else
+    punpckhwd    m%2, m%1
+    punpcklwd    m%1, m%1
+    psrad        m%2, 16
+    psrad        m%1, 16
+%endif
+%endmacro